PR-domain containing nucleic acids, polypeptides, antibodies and methods

ABSTRACT

The invention provides an isolated PR Family Member (PFM) nucleic acid molecule that contains a PFM PR domain nucleotide sequence, a PFM ZF domain nucleotide sequence, or a modification thereof. The invention also provides an isolated PFM nucleic acid molecule that contains a nucleotide sequence that encodes a PFM PR domain polypeptide, or that encodes a PFM ZF domain polypeptide, or that encodes an immunologically equivalent modification thereof. Also provided are isolated PFM oligonucleotides. The invention also provides methods for detecting a PFM nucleic acid molecule in a sample. Further provided is a method of modulating cell growth by expressing an encoded PFM polypeptide in the cell. Also provided is an isolated PFM polypeptide, containing a PFM PR domain amino acid sequence, or a PFM ZF domain amino acid sequence, or a modification thereof. The invention also provides an isolated PFM peptide, containing at least 8 contiguous amino acids of a PFM polypeptide. Also provided is an antibody or antigen binding fragment thereof, which specifically binds a PFM polypeptide. Further provided is a method for detecting PFM polypeptide in a sample, by contacting the sample with a PFM antibody and detecting specifically bound antibody.

This application is a continuation of application Ser. No. 09/389,956, filed Sep. 3, 1999, now U.S. Pat. No. 6,586,579.

This invention was made in part with government support under grant number RO1 CA76146, awarded by the National Institutes of Health. Accordingly, the United States government has certain rights in this invention.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to proliferative disorders such as cancer and, more specifically, to PR-domain containing genes and gene products that can be used to diagnose and treat proliferative disorders.

2. Background Information

Cancer is one of the leading causes of death in industrialized nations. Cancerous tumors result when a cell escapes from its normal growth regulatory mechanisms and proliferates in an uncontrolled fashion. Cells from the primary tumor generally metastasize to vital organs if treatment of the primary tumor is either not complete or not initiated early enough. Thus, early diagnosis and effective treatment of tumors is essential for survival.

Cancer involves the clonal replication of populations of cells that have gained competitive advantage over normal cells through the alteration of regulatory genes. Regulatory genes can be broadly classified into “oncogenes” which, when activated or overexpressed promote unregulated cell proliferation, and “tumor suppressor genes” which, when inactivated or underexpressed fail to prevent abnormal cell proliferation. Loss of function or inactivation of tumor suppressor genes is thought to play a central role in the initiation and progression of a significant number of human cancers.

A number of tumor suppressor genes have been identified that, when inactivated, are involved in the initiation or progression of human cancers. Known tumor suppressor genes include RB, p53, DCC, APC/MCC, NF1, NF2, WT1, VHL, BRCA1, MST1 and WAF1/CIP1. Approaches for treating cancer by modulating the function of several of these tumor suppressor genes, either with pharmaceutical compounds that target their encoded proteins, or by gene therapy methods, have yielded promising results in animal models and in human clinical trials.

Approaches for diagnosing and prognosing cancer by identifying mutations in tumor suppressor genes have also been developed. For example, identifying individuals containing germline mutations in known tumor suppressor genes has permitted the identification of individuals at increased risk of developing cancer. Such individuals are then closely monitored or treated prophylactically to improve their chance of survival. Identifying the pattern of alterations of known tumor suppressor genes in biopsy samples is also being used to determine the presence or stage of a tumor. Being able to determine whether a cancer is benign or malignant, or at an early or late stage of progression, provides the patient and clinician with a more accurate prognosis and can be used to determine and monitor the course of treatment.

One important family of tumor suppressor genes that has recently been identified are PR-domain containing genes. A “PR domain” is a motif of approximately 100 to 125 amino acids first identified as a region of homology between the Rb-binding zinc finger protein RIZ, and the transcriptional repressor protein PRD1-BF1/Blimp1, which promotes B-cell differentiation (Buyse et al., Proc. Natl. Acad. Sci. USA 92:4467-4471 (1995); Huang, Cell 78:9 (1994)). A PR domain motif is also found in the MDS1-EVI1 myeloid leukemia gene (Fears et al., Proc. Natl. Acad. Sci. USA 93:1642-1647 (1996)). PR domain-encoding genes have also been identified in other mammals and in lower organisms, including C. elegans and Drosophila, suggesting an evolutionarily conserved function for this domain.

Several observations indicate that PR-domain containing gene products are negative regulators of cell growth and tumorigenesis, whereas the PR-deficient products of these genes are involved in growth promotion and oncogenesis. For example, the PR region of MDS1-EVI1 is often disrupted by leukemia-associated chromosomal insertions and translocations. These disruptions result in loss of the PR-containing MDS1-EVI1 product and selective retention of the PR-deficient EVI1 product. In contrast, the PR-EVI1 product is overexpressed in some tumor cells, and acts as an oncogene (Morishita et al., Cell 54:831-840 (1988); Morishita et al., Proc. Natl. Acad. Sci. USA 89:3937-3941 (1992))

Similarly, the RIZ gene produces two products, a PR-containing protein, RIZ1, and a PR-deficient protein, RIZ2, which is generated from an internal promoter. RIZ1 is commonly absent or underexpressed in a number of human neoplasias, including breast cancer, neuroblastoma and lung cancer. In these cases, the PR-deficient product, RIZ2, is expressed at normal levels (He et al., Cancer Res. 58:4238-4244 (1998)). These results suggest that the PR-containing RIZ1 product is a negative regulator of cell proliferation and tumorigenesis, whereas maintenance of RIZ2 expression may be required for oncogenesis.

As further evidence that RIZ is a tumor suppressor gene, forced expression of the RIZ1 product in breast cancer cells causes cell cycle arrest at the G2/M phase of the cell cycle, and programmed cell death (He et al., Cancer Res. 58:4238-4244 (1998)). Additionally, consistent with a role of RIZ1 in growth suppression, mice in which RIZ1, but not RIZ2, is inactivated, are tumor prone.

A third PR domain-containing gene, PRDI-BF1/BLIMP1 is also likely to be a tumor suppressor gene. PRD1-BF1/BLIMP1 maps to the 6q21 region commonly deleted in non-Hodgkin's lymphoma (Mock et al., Genomics 37:24-28 (1996)) and is thus a strong candidate tumor suppressor for B-cell non-Hodgkin's lymphoma. Additionally, PRDI-BF1/BLIMP1 is a transcriptional repressor of c-Myc (Lin et al., Science 276:596-598 (1997)), which is an oncogene critically involved in B cell lymphoma.

In view of the importance of tumor suppressor genes and related molecules in the detection and treatment of cancer, there exists a need to identify additional tumor suppressor genes. In particular, in view of the established role of PR-domain containing genes as tumor suppressor genes, there exists a need to identify and characterize additional PR-domain family members. The present invention satisfies this need and provides related advantages as well.

SUMMARY OF THE INVENTION

The invention provides an isolated PR Family Member (PFM) nucleic acid molecule that contains a PFM PR domain nucleotide sequence selected from the group consisting of SEQ ID NOS:17, 19, 21, 23, 25 and 27; or a PFM ZF domain nucleotide sequence selected from the group consisting of SEQ ID NOS:63, 65, 67, 69, 71, 73 and 75; or a modification thereof.

The invention also provides an isolated PFM nucleic acid molecule that contains a nucleotide sequence that encodes a PFM PR domain polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NOS:18, 20, 22, 24, 26 and 28; or a nucleotide sequence that encodes a PFM ZF domain polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NOS:64, 66, 68, 70, 72, 74 and 76; or a nucleotide sequence that encodes an immunologically equivalent modification thereof.

Further provided is an isolated PFM oligonucleotide, containing between 15 and 300 contiguous nucleotides of SEQ ID NOS:2, 4, 6, 8, 10, 12, 14 or 16.

Also provided are methods for detecting a PFM nucleic acid molecule in a sample. In one embodiment, the method consists of contacting the sample with a PFM nucleic acid molecule under conditions that allow specific hybridization to PFM nucleic acid, and detecting specific hybridization. In another embodiment, the method consists of contacting the sample with a PFM primer pair under conditions that allow amplification of PFM nucleic acid, and detecting amplified PFM nucleic acid.

Further provided is a method of modulating cell growth. The method consists of introducing a vector containing a PFM nucleic acid operatively linked to a promoter of RNA transcription into a host cell, and expressing encoded PFM polypeptide in an amount effective to modulate growth of the cell.

The invention also provides an isolated PFM polypeptide, containing a PFM PR domain amino acid sequence selected from the group consisting of SEQ ID NOS:18, 20, 22, 24, 26 and 28; or a PFM ZF domain amino acid sequence selected from the group consisting of SEQ ID NOS:64, 66, 68, 70, 72, 74 and 76; or a modification thereof.

Also provided is an isolated PFM peptide, containing at least 8 contiguous amino acids of SEQ ID NOS:2, 4, 6, 8, 10, 12, 14 and 16.

The invention also provides an antibody or antigen binding fragment thereof, which specifically binds a PFM polypeptide. Further provided is a method for detecting PFM polypeptide in a sample, by contacting the sample with a PFM antibody under conditions that allow specific binding of the antibody to PFM polypeptide, and detecting specifically bound antibody.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows the nucleotide sequence (SEQ ID NO:1) and FIG. 1B shows the deduced amino acid sequence SEQ ID NO:2) of PFM1. The zinc finger motifs are shown by underlining, and the regions of similarity between PFM polypeptides including and extending beyond the A, B and C boxes are shown by italics, in FIG. 1B.

FIG. 2A shows the nucleotide sequence (SEQ ID NO:3) and FIG. 2B shows the deduced amino acid sequence SEQ ID NO:4) of PFM2. The zinc finger motifs are shown by underlining, and the regions of similarity between PFM polypeptides including and extending beyond the A, B and C boxes are shown by italics, in FIG. 2B.

FIG. 3A shows the nucleotide sequence (SEQ ID NO:5) and FIG. 3B shows the deduced amino acid sequence SEQ ID NO:6) of mPFM2a. The zinc finger motifs are shown by underlining, and the regions of similarity between PFM polypeptides including and extending beyond the A, B and C boxes are shown by italics, in FIG. 3B.

FIG. 4A shows the nucleotide sequence (SEQ ID NO:7), and FIG. 4B shows the deduced amino acid sequence SEQ ID NO:8) of mPFM2b.

FIG. 5A shows the nucleotide sequence (SEQ ID NO:9) and FIG. 5B shows the deduced amino acid sequence SEQ ID NO:10) of PFM3a. The zinc finger motifs are shown by underlining, and the regions of similarity between PFM polypeptides including and extending beyond the A, B and C boxes are shown by italics, in FIG. 5B.

FIG. 6A shows the nucleotide sequence (SEQ ID NO:11) and FIG. 6B shows the deduced amino acid sequence SEQ ID NO:12) of PFM3b.

FIG. 7A shows the nucleotide sequence (SEQ ID NO:13) and FIG. 7B shows the deduced amino acid sequence SEQ ID NO:14) of PFM4. The zinc finger motifs are shown by underlining, and the regions of similarity between PFM polypeptides including and extending beyond the A, B and C boxes are shown by italics, in FIG. 7B.

FIG. 8A shows the nucleotide sequence (SEQ ID NO:15) and FIG. 8B shows the deduced amino acid sequence SEQ ID NO:16) of PFM5. The zinc finger motif is shown by underlining, and the regions of similarity between PFM polypeptides including and extending beyond the A, B and C boxes are shown by italics, in FIG. 8B.

FIG. 9A shows the nucleotide sequence (SEQ ID NO:77) and FIG. 9B shows the deduced amino acid sequence SEQ ID NO:78) of PKZL1.

FIG. 10A shows the nucleotide sequence (SEQ ID NO:79) and FIG. 10B shows the deduced amino acid sequence SEQ ID NO:80) of PKZL2.

FIG. 11A shows a schematic representation of the structure of PFM1, and also shows the boundaries of the probes and primers used to detect PFM1 expression. FIG. 11B shows expression of PFM1 in various human tissues by Northern blot analysis. FIG. 11C show expression of PFM1 in various human tissues by RT-PCR analysis. FIG. 11D show expression of PFM1 in NGF-treated and non-treated PC12 cells.

FIG. 12A shows a schematic representation of the structure of PFM2, mPFM2a and mPFM2b. FIG. 12B shows expression of PFM2 in various human tissues by Northern blot analysis. FIG. 12C show expression of PFM2 in various human tissues by RT-PCR analysis.

FIG. 13A shows a schematic representation of the structure of PFM3a and PFM3b. FIG. 13B shows expression of PFM3 in various human tissues by RT-PCR analysis.

FIG. 14 shows a schematic representation of the structure of PFM4.

FIG. 15A shows a schematic representation of the structure of PFM5. FIG. 15B shows expression of PFM5 in various mouse tissues by Northern blot analysis. FIG. 15C show expression of PFM5 in various human tissues by RT-PCR analysis.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides novel “PR Family Member,” or “PFM,” nucleic acid molecules, polypeptides, antibodies, modulatory compounds, and related methods. The PFM nucleic acids and polypeptides of the invention are important regulators of cell proliferation. Therefore, the molecules and methods of the invention can be used to modulate cell proliferation so as to prevent or treat proliferative disorders, including cancer. Additionally, the molecules and methods of the invention can be used to diagnose and prognose proliferative disorders.

PFM nucleic acid molecules and polypeptides are generally characterized by encoding or containing a “PR domain” and a “zinc finger domain.” Exemplary PFM nucleic acid molecules include RIZ, MDS1-EVI1 and PRDI-BF1 (BLIMP1).

The PR domain has been demonstrated to be a protein binding motif involved in the regulation of gene expression (Huang et al., J. Biol. Chem. 273:15933-15940 (1998); Soderholm et al., Leukemia 11:352-358 (1997)). In particular, the PR domain is considered to function in the assembly of chromatin-based multiprotein complexes involved in either euchromatin-mediated gene activation, or heterochromatin-mediated gene silencing. Lack or inactivation of the PR domain can thus specifically inactivate the chromatin-associated functions of a PFM, without affecting other activities such as DNA binding and chromatin-independent transcriptional activation or repression. Differential chromatin regulation by the PR+ and PR− forms of a PFM gene may therefore underlie the opposite roles of these products in tumorigenesis.

The PR domain is about 100 to 125 amino acids in length, and contains three highly conserved sequences, designated the A, B and C boxes, each of which consists of about 6 to 12 amino acids. Each of boxes A, B and C is encoded by a separate exon. Alternative exon usage of the A, B and C boxes, and transcription from internal promoters, can result in PFM transcripts and polypeptides containing all, some or none of the A, B or C boxes.

PFM nucleic acid molecules and encoded polypeptides additionally contain a zinc finger domain, or “ZF domain.” Generally, the ZF domain contains one or several C2H2 or Krüppel-like Zinc finger motifs, which can be represented by the structure: Cys-X2-Cys-X12-His-X3-His. However, a zinc finger motif of a PFM can have an amino acid other than Cys or His at one or more of the four conserved positions, and/or alternative spacings between the four conserved positions. The zinc finger motif is found in at least 300 human genes, and is known to specifically bind DNA or RNA sequences (Bellefroid et al., DNA 8:377-387 (1989).

The PFM nucleic acid molecules and polypeptides of the invention are designated PFM1, PFM2, mPFM2a, mPFM2b, PFM3a, PFM3b, PFM4 and PFM5. The nucleotide sequences of these PFM nucleic acid molecules are shown in FIGS. 1A-8A, respectively, and are set forth as SEQ ID NO:1 (PFM1); SEQ ID NO:3 (PFM2); SEQ ID NO:5 (mPFM2a); SEQ ID NO:7 (mPFM2b); SEQ ID NO:9 (PFM3a); SEQ ID NO:11 (PFM3b); SEQ ID NO:13 (PFM4); and SEQ ID NO:15 (PFM5). The amino acid sequences of the encoded PFM polypeptides are also shown in FIGS. 1B-8B, respectively, and are set forth as SEQ ID NO:2 (PFM1); SEQ ID NO:4 (PFM2); SEQ ID NO:6 (mPFM2a); SEQ ID NO:8 (mPFM2b) SEQ ID NO:10 (PFM3a); SEQ ID NO:12 (PFM3b) SEQ ID NO:14 (PFM4); and SEQ ID NO:16 (PFM5).

The nucleotide (nt) boundaries of the PR domains, and of the A, B and C boxes thereof, of PFM1, PFM2, mPFM2a, PFM3a, PFM4 and PFM5, with respect to the sequences shown in FIGS. 1A, 2A, 3A, 5A, 7A and 8A, respectively, with their corresponding SEQ ID NOS, are provided in Table 1, below. The amino acid (aa) boundaries of the PR domains, and of the A, B and C boxes thereof, of PFM1, PFM2, mPFM2a, PFM3a, PFM4 and PFM5, with respect to the sequences shown in FIGS. 1B, 2B, 3B, 5B, 7B and 8B, respectively, with their corresponding SEQ ID NOS, are also provided in Table 1, below.

TABLE 1 PFM PR DOMAIN A BOX B BOX C BOX PFM1 nt 1372–1740 nt 1420–1455 nt 1549–1584 nt 1690–1707 (SEQ ID NO:17) (SEQ ID NO:29) (SEQ ID N0:31) (SEQ ID NO:33) aa 412–534 aa 428–439 aa 471–482 aa 518–523 (SEQ ID NO:18) (SEQ ID NO:30) (SEQ ID NO:32) (SEQ ID NO:34) PFM2 nt 172–402 NOT APPLICABLE nt 229–264 nt 370–387 (SEQ ID NO:19) (SEQ ID NO:35) (SEQ ID NO:37) aa 1–77 aa 20–31 aa 67–72 (SEQ ID NO:20) (SEQ ID NO:36) (SEQ ID NO:38) mPFM2a nt 118–474 nt 163–198 nt 289–324 nt 430–447 (SEQ ID NO:21) (SEQ ID NO:39) (SEQ ID NO:41) (SEQ ID NO:43) aa 14–131 aa 29–40 aa 71–82 aa 118–123 (SEQ ID NO:22) (SEQ ID NO:40) (SEQ ID NO:42) (SEQ ID NO:44) PFM3a nt 652–1020 nt 699–735 nt 832–867 nt 973–990 (SEQ ID NO:23) (SEQ ID NO:45) (SEQ ID NO:47) (SEQ ID NO:49) aa 218–340 aa 234–245 aa 277–289 aa 325–330 (SEQ ID NO:24) (SEQ ID NO:46) (SEQ ID NO:48) (SEQ ID NO:50) PFM4 nt 277–618 nt 332–357 nt 436–471 nt 577–594 (SEQ ID NO:25) (SEQ ID NO:51) (SEQ ID NO:53) (SEQ ID NO:55) aa 46–159 aa 61–72 aa 99–110 aa 146–151 (SEQ ID NO:26) (SEQ ID NO:52) (SEQ-ID NO:54) (SEQ ID NO:56) PFM5 nt 1306–1647 nt 1336–1368 nt 1453–1500 nt 1606–1623 (SEQ ID NO:27) (SEQ ID NO:57) (SEQ ID NO:59) (SEQ ID NO:61) aa 25–138 aa 35–45 aa 74–89 aa 125–130 (SEQ ID NO:28) (SEQ ID NO:58) (SEQ ID NO:60) (SEQ ID NO:62)

When the PFM polypeptides of the invention are aligned with other PFM polypeptides, including RIZ1, BLIMP1 and MDS1-EVI1, it is apparent that there is a region of sequence similarity that extends beyond the A, B and C boxes set forth in Table I. The amino acid (aa) boundaries of the region of sequence similarity including and extending beyond the A, B and C boxes of the PR domains of PFM1, PFM2, mPFM2a, PFM3a, PFM4 and PFM5 are shown by italics in FIGS. 1B, 2B, 3B, 5B, 7B and 8B, respectively.

The nucleotide (nt) boundaries of the zinc finger (ZF) domains of PFM1, PFM2, mPFM2a, PFM3a, PFM4 (2 separate domains) and PFM5, with respect to the sequences shown in FIGS. 1A, 2A, 3A, 5A, 7A and 8A, respectively, with their corresponding SEQ ID NOS, are provided in Table 2, below. The amino acid (aa) boundaries of the ZF domains of PFM1, PFM2, mPFM2a, PFM3a, PFM4 (2 separate domains) and PFM5, with respect to the sequences shown in FIGS. 1B, 2B, 3B, 5B, 7B and 8B, respectively, with their corresponding SEQ ID NOS, are also provided in Table 2, below. The amino acid (aa) boundaries of each of the individual zinc finger motifs within the ZF domains of PFM1, PFM2, mPFM2a, PFM3a, PFM4 and PFM5 are shown by underlining in FIGS. 1B, 2B, 3B, 5B, 7B and 8B, respectively.

TABLE 2 Zinc Finger Domain Zinc Finger Domain PFM (nucleotides) (amino acids) PFM1 nt 1897–2379 aa 587–747 (SEQ ID NO:63) (SEQ ID NO:64) PFM2 nt 523–1047 aa 118–292 (SEQ ID NO:65) (SEQ ID NO:66) mPFM2a nt 634–2005 aa 186–642 (SEQ ID NO:67) (SEQ ID NO:68) PFM3a nt 1321–1635 aa 441–545 (SEQ ID NO:69) (SEQ ID NO:70) PFM4 nt 691–756 aa 184–205 (SEQ ID NO:71) (SEQ ID NO:72) nt 1099–1329 aa 320–396 (SEQ ID NO:73) (SEQ ID NO:74) PFM5 nt 1702–1767 aa 157–178 (SEQ ID NO:75) (SEQ ID NO:76)

Both PFM2 and mPFM2a polypeptides contain a sequence motif, LXCXE, which is also present in RIZ gene products. The LXCXE motif is known to bind the retinoblatoma (Rb) tumor suppressor gene product (Buyse et al., J. Virol. 71:6200-62-3 (1997)). The LXCXE motif in PFM2 has the sequence LGCKE (SEQ ID NO:89), which corresponds to amino acids 110-114 of the sequence shown in FIG. 2B, and is encoded by nucleotides 498-513 (SEQ ID NO:88) of the sequence shown in FIG. 2A. The LXCXE motif in mPFM2a has the sequence LGCEE (SEQ ID NO:91), which corresponds to amino acids 178-182 of the sequence shown in FIG. 3B, and is encoded by nucleotides 610-624 (SEQ ID NO:90) of the sequence shown in FIG. 3A.

PFM4 additionally contains a domain of approximately 100 amino acids having about 35-40% identity to the KRAB-domain-containing zinc finger protein 133 (ZNF133). This domain is designated PKZL, for “PR and KRAB zinc finger protein-linked.” The PKZL domain of PFM4 corresponds to amino acids 207-306 of the sequence shown in FIG. 7B, and is encoded by nucleotides 760-1059 of the sequence shown in FIG. 7A. The PKZL domain likely is important in mediating protein-protein interactions with cellular regulatory molecules.

The PKZL domain is also found in two other KRAB-domain-containing zinc finger proteins, designated PKZL1 and PKZL2. The nucleotide sequence of PKZL1 (SEQ ID NO:77) is shown in FIG. 9A, and the encoded amino acid sequence of PKZL1 (SEQ ID NO:78) is shown in FIG. 9B. The nucleotide sequence of PKZL2 (SEQ ID NO:79) is shown in FIG. 10A, and the encoded amino acid sequence of PKZL2 (SEQ ID NO:80) is shown in FIG. 10B. The amino acid (aa) boundaries of the KRAB Domain, PKZL and ZF domains of PKZL1 and PKZL2, with respect to the sequences shown in FIGS. 9B and 10B, respectively, are provided in Table 3, below.

TABLE 3 PKZL KRAB Domain PKZL Domain ZF Domain PKZL1 aa 9–65 aa 99–192 aa 197–509 PKZL2 aa 1–39 aa 63–172 aa 204–515

The cDNA structures of PFM1, PFM2, mPFM2a, mPFM2b, PFM3a, PFM3b, PFM4 and PFM5, with the boundaries of their PR domains, A, B and C boxes, zinc finger motifs, LXCXE motif, and PKZL domain indicated, are schematically depicted in FIGS. 11A, 12A, 13A, 14 and 15A.

As shown in FIGS. 12A and 13A, certain of the PFM genes disclosed herein exist as alternatively spliced products. For example, the PFM2 sequence disclosed herein lacks the PR domain A box. The mPFM2 exists as a PR+ form, namely mPFM2a, and a PR− form lacking the PR domain C box, namely mPFM2b. Likewise, PFM3 exists as a PR+ form, namely PFM3a, and a PR− form lacking the PR domain B and C boxes. Additionally, as described further in the Examples, below, mRNA transcripts of several different sizes are observed for certain of the PFM genes, consistent with alternative exon usage.

The PFM genes disclosed herein are localized to regions of human chromosomes predicted to harbor tumor suppressor genes, because deletion of these regions is closely associated with various human tumors. In particular, PFM1 localizes to chromosome band 12q23-q24.1, a region commonly deleted in ovarian cancer, pancreatic cancer and gastric cancer; PFM2 localizes to chromosome band 4q25-4q26, a region commonly deleted in ovarian cancer, breast cancer, lung cancer and hepatoma; PFM3 localizes to chromosome band 5q21, a region often deleted in ovarian cancer, colon cancer, lung cancer and gastric cancer; PFM4 localizes to chromosome band 16q24, a region deleted in prostate cancer, breast cancer, ovarian cancer and hepatoma; and PFM5 localizes to chromosome band 4q21.1, which is deleted in mesothelioma, lung cancer, colon cancer and hepatoma. These observations are consistent with a role for these PFMs as tumor suppressors.

PFM Nucleic Acid Molecules

The invention provides isolated PFM nucleic acid molecules. The isolated PFM nucleic acid molecules of the invention can be used in a variety of diagnostic and therapeutic applications. For example, as described in more detail below, the isolated PFM nucleic acid molecules of the invention can be used as probes and primers to detect PFM nucleic acid molecules in samples; as templates for the recombinant expression of PFM polypeptides; in two-hybrid assays to identify cellular molecules that bind PFM; and in in vivo and ex vivo gene therapy applications to positively or negatively modulate cell proliferation.

In one embodiment, the invention provides an isolated PFM nucleic acid molecule containing a PFM PR domain nucleotide sequence selected from the group consisting of SEQ ID NOS:17, 19, 21, 23, 25 and 27. In another embodiment, the invention provides an isolated PFM nucleic acid molecule containing a PFM ZF domain nucleotide sequence selected from the group consisting of SEQ ID NOS:63, 65, 67, 69, 71, 73 and 75. Modifications of these sequences that hybridizes thereto under moderately stringent conditions, and modifications of these sequences having at least 60% identity thereto are also provided.

Exemplary isolated PFM nucleic acid molecules provided by the invention that contain a PFM PR domain or that contain a PFM ZF domain are nucleic acid molecules having the sequence of SEQ ID NOS:1, 3, 5, 7, 8, 11, 13 or 15, or modification thereof that hybridizes thereto under moderately stringent conditions.

Other exemplary isolated PFM nucleic acid molecules of the invention contain both the PR domain and the ZF domain of a PFM, as set forth above, and, optionally, can also contain PFM sequence between the PR domain and the ZF domain.

The term “isolated,” in reference to a PFM nucleic acid molecule is intended to mean that the molecule is substantially removed or separated from components with which it is naturally associated, or otherwise modified by the hand of man. Thus, the term “isolated PFM nucleic acid molecule” excludes PFM nucleic acid molecules as they exist in nature.

The term “nucleic acid molecule,” as used herein, refers to an oligonucleotide or polynucleotide of natural or synthetic origin. A nucleic acid molecule can be single- or double-stranded genomic DNA, cDNA or RNA, and can represent the sense strand, the antisense strand, or both.

The term “moderately stringent conditions,” as used herein, refers to hybridization conditions that permit a nucleic acid molecule to bind a nucleic acid that has substantial identity to the recited sequence. Moderately stringent conditions are conditions equivalent to hybridization of filter-bound nucleic acid in 50% formamide, 5× Denhart's solution, 5×SSPE, 0.2% SDS at 42° C., followed by washing in 0.2×SSPE, 0.2% SDS, at 50°. In contrast, “highly stringent conditions” are conditions equivalent to hybridization of filter-bound nucleic acid in 50% formamide, 5× Denhart's solution, 5×SSPE, 0.2% SDS at 42° C., followed by washing in 0.2×SSPE, 0.2% SDS, at 65°. Other suitable moderately stringent and highly stringent hybridization buffers and conditions are well known to those of skill in the art and are described, for example, in Sambrook et al., Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratory, New York (1992) and in Ansubel et al., Current Protocols in Molecular Biology, John Wiley and Sons, Baltimore, Md. (1998).

In general, a nucleic acid molecule that hybridizes to a recited sequence under moderately stringent conditions will have greater than about 60% identity, such as greater than about 70% identity, preferably greater than about 80% identity to the reference sequence over the length of the two sequences being compared. A nucleic acid molecule that hybridizes to a recited sequence under highly stringent conditions will generally have greater than about 90% identity, including greater than about 95% identity, to the reference sequence over the length of the two sequences being compared. Identity of any two nucleic acid sequences can be determined by those skilled in the art based, for example, on a BLAST 2.0 computer alignment, using default parameters. BLAST 2.0 searching is available at www.ncbi.nlm .nih.gov/gorf/bl2.html., as described by Tatiana et al., FEMS Microbiol Lett. 174:247-250 (1999).

Thus, a “modification” of a reference nucleic acid sequence can include one or several nucleotide additions, deletions, or substitutions with respect to the recited sequence. Such modifications can correspond to variations that are made deliberately, or which occur as mutations during nucleic acid replication.

Exemplary “modifications” of the recited PFM sequences include sequences that correspond to homologs of other species, such as primates, mouse, rat, rabbit, bovine, porcine, ovine, canine or feline species. The sequences of corresponding PFMs of non-human species can be determined by methods known in the art, such as by PCR or by screening genomic, cDNA or expression libraries.

Furthermore, exemplary “modifications” of the recited PFM can correspond to splice variant forms of recited PFM sequences. Thus, for example, a modification of a PFM nucleic acid molecule of the invention can lack one or more of the exons that encode the A, B or C boxes of the PR domain. Exon usage by splice variants of PFM nucleic acid molecules can be readily determined by those skilled in the art by comparing the sequence of the PFM cDNA to the sequence of the corresponding PFM genomic DNA.

Additionally, a “modification” of a reference sequence can include one or more non-native nucleotides, having, for example, modifications to the base, the sugar, or the phosphate portion, or having a modified phosphodiester linkage. Such modifications can be advantageous in increasing the stability of the nucleic acid molecule.

Furthermore, a “modification” of a reference sequence can include, for example, a detectable moiety, such as a radiolabel, a fluorochrome, a ferromagnetic substance, a luminescent tag or a detectable binding agent such as biotin. Such modifications can be advantageous in applications where detection of a PFM nucleic acid molecule is desired.

In another embodiment, the invention provides an isolated PFM nucleic acid molecule containing a nucleotide sequence that encodes a PFM PR domain polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NOS:18, 20, 22, 24, 26 and 28. In a further embodiment, the invention provides a PFM ZF domain polypeptide having an amino acid sequence selected from the group consisting of SEQ ID NOS:64, 66, 68, 70, 72, 74 and 76. Nucleic acid molecules having nucleic acid sequences that encode modified polypeptides that are immunologically equivalent to the recited PFM amino acid sequences are also provided. The term “immunologically equivalent” is described further below in regard to PFM polypeptides.

The term “isolated PFM nucleic acid molecule” specifically excludes nucleic acid molecules consisting of certain nucleotide sequences, such as Expressed Sequence Tags (ESTs), Sequence Tagged Sites (STSs) and genomic fragments, deposited in public databases such as the nr, dbest, dbsts, gss and htgs databases, which are available for searching at www.ncbi.nlm.nih.gov/blast/blast.cgi?Jform=0, using the program BLASTN 2.0.9 [May-07-1999] described by Altschul et al., Nucleic Acids Res. 25:3389-3402 (1997).

In particular, the term “PFM nucleic acid molecule” specifically excludes nucleic acid molecules consisting of any of the nucleotide sequences having the Genbank (gb), EMBL (emb) or DDBJ (dbj) Accession numbers set forth in Table 4, below:

TABLE 4 PFM PR domain ZF domain PFM1 gb|AC007622.10; gb|AI767612.1; gb|AQ680319.1; gb|AI200380; gb|AQ589875.1; gb|AI031897; gb|T07037; gb|AI274279; dbj|D77868; gb|W95618 gb|AA564783; gb|AA052953; gb|AI206448; gb|W95619; gb|T75408; gb|R14633; emb|F13077; gb|T67867; gb|AA074438; emb|F08157; gb|AA361586; gb|W95618; gb|AI422938.1; gb|AA547654; gb|AI422940; gb|AA542340; gb|AA151863; gb|W23287; gb|AC007622.10; gb|B90692; gb|AQ119702 PFM2 gb|AA917968; gb|AQ491694.1; gb|AI528057; emb|X96881; gb|AA884744; gb|AI315936; gb|AI049009; gb|AI197291; mPFM2 gb|AI315936; emb|X96881; gb|AI528057; gb|AI893133.1; gb|AI049009; gb|W11621; gb|AA511711; gb|AA917968; gb|AI894176.1; gb|AA884744; gb|AI314715; gb|AI197291; gb|AI785273.1; gb|AI521783.1; gb|W33556; dbj|AU018120; dbj|AU017087; gb|M79273; gb|AA014148; gb|AI854760.1; gb|AI894050.1; gb|AQ451739.1; gb|AQ480567.1; gb|AQ120015; gb|AQ491694.1; PFM3 gb|AI243539; gb|AI862130.1; gb|AI324149; gb|AA546652; gb|N83355; gb|AI914660.1; gb|AA917645; gb|AI322509; gb|AI322509; gb|AI348223; gb|AA018011; gb|AA917645; gb|AA008751; gb|N29774; gb|AC008606.1 gb|AA008751; gb|AA018011; gb|AC008606.1 PFM4 gb|AC007046.1; gb|AC007046.1; gb|AF03975 emb|Z96314; gb|AF114816.1; gb|AF114817.1; emb|AL049650.8; gb|M20675; gb|U28251; emb|AL031673.16; emb|AL049942.1; emb|Z98745; gb|AC005678; gb|AQ772417.1; gb|AQ266860.1; emb|AL047439.1; gb|T88890; gb|T09047; gb|AA341469; gb|AI810272.1; gb|T70255; gb|W85779; gb|T23204; gb|AA385857; gb|AI603959.1; gb|AA612532; PFM5 gb|AI570404.1; gb|AI594999.1; gb|G18801 gb|AI594999.1; gb|AA056286; gb|H43774; gb|AA054104; gb|H83463; gb|R88858;

The invention also provides isolated PFM oligonucleotides containing at least 15 contiguous nucleotides of PFM1, hPFM2, mPFM3, PFM4, or PFM5. As used herein, the term “oligonucleotide” refers to a nucleic acid molecule that includes at least 15 contiguous nucleotides from the reference nucleotide sequence, can include at least 16, 17, 18, 19, 20 or at least 25 contiguous nucleotides, and often includes at least 30, 40, 50, 60, 70, 80, 90, 100, 125, 150, 175, 200, 225, 250, 275, 300, 325, up to 350 contiguous nucleotides from the reference nucleotide sequence.

In one embodiment, the isolated PFM oligonucleotides contain a nucleotide sequence that encodes a PR domain A, B, or C box. Thus, the invention provides isolated oligonucleotides containing a nucleotide sequence selected from the group consisting of SEQ ID NOS:29, 31, 33, 35, 37, 39, 41, 43, 45, 47, 49, 51, 53, 55, 57, 59 and 61.

In another embodiment, the invention provides isolated PFM oligonucleotides that contain a nucleotide sequence that encodes one or more ZF domain zinc finger motifs. The PFM zinc finger motifs of PFM nucleic acid molecules are underlined in FIGS. 1B, 2B, 3B, 5B, 7B and 8B.

In yet another embodiment, the invention provides an isolated PFM oligonucleotide that contains at least a part of the nucleotide sequence that encodes the PKZL domain of PFM4, which is nucleotides 760-1059 of the sequence shown in FIG. 7A.

In a further embodiment, the invention provides isolated PFM oligonucleotides that contain a nucleotide sequence that encodes the RB-binding LXCXE motif of PFM2 or mPFM2. Thus, the invention provides an oligonucleotide selected from the group consisting of SEQ ID NOS:88 and 90.

The PFM oligonucleotides of the invention that contain at least 15 contiguous nucleotides from the reference PFM nucleotide sequence are able to hybridize to PFM under moderately stringent hybridization conditions and thus can be advantageously used, for example, as probes to detect PFM DNA or RNA in a sample, and to detect splice variants thereof that contain or lack particular PFM domains; as sequencing or PCR primers; as antisense reagents to block transcription of PFM RNA in cells; or in other applications known to those skilled in the art in which hybridization to a PFM is desirable.

In one embodiment, the invention provides oligonucleotides containing at least 15 contiguous PFM nucleotides that are able to “specifically hybridize” with a PFM nucleic acid molecule. As used herein, the term “specifically hybridize” refers to the ability of a nucleic acid molecule to hybridize, under moderately stringent conditions as described above, to the reference PFM nucleic acid molecule, without hybridization under the same conditions with nucleic acid molecules that are not PFMs, such as actin cDNA.

In one embodiment, the invention provides a primer pair for detecting PFM nucleic acid. The primer pair contains two PFM oligonucleotides. The primer pair can be used, for example, to amplify PFM DNA by RT-PCR or PCR. Exemplary PFM primer pairs and their uses are provided in Examples I-III and V, below.

The isolated PFM nucleic acid molecules and oligonucleotides of the invention can be produced or isolated by methods known in the art. The method chosen will depend, for example, on the type of nucleic acid molecule one intends to isolate. Those skilled in the art, based on knowledge of the nucleotide sequences disclosed herein, can readily isolate PFM nucleic acid molecules as genomic DNA, or desired introns, exons or regulatory sequences therefrom; as full-length cDNA or desired fragments therefrom; or as full-length mRNA or desired fragments therefrom, by methods known in the art.

One useful method for producing an isolated PFM nucleic acid molecule of the invention involves amplification of the nucleic acid molecule using the polymerase chain reaction (PCR) and PFM-specific primers and, optionally, purification of the resulting product by gel electrophoresis. Either PCR or reverse-transcription PCR (RT-PCR) can be used to produce a PFM nucleic acid molecule having any desired nucleotide boundaries. Desired modifications to the nucleic acid sequence can also be introduced by choosing an appropriate primer with one or more additions, deletions or substitutions. Such nucleic acid molecules can be amplified exponentially starting from as little as a single gene or mRNA copy, from any cell, tissue or species of interest.

A futher method of producing an isolated PFM nucleic acid molecule of the invention is by screening a library, such as a genomic library, cDNA library or expression library, with a detectable agent. Such libraries are commercially available or can be produced from any desired tissue, cell, or species of interest using methods known in the art. For example, a cDNA or genomic library can be screened by hybridization with a detectably labeled nucleic acid molecule having a nucleotide sequence disclosed herein. Additionally, an expression library can be screened with an antibody raised against a polypeptide corresponding to the coding sequence of a PFM nucleic acid disclosed herein. The library clones containing PFM molecules of the invention can be isolated from other clones by methods known in the art and, if desired, fragments therefrom can be isolated by restriction enzyme digestion and gel electrophoresis.

Furthermore, isolated PFM nucleic acid molecules and oligonucleotides of the invention can be produced by synthetic means. For example, a single strand of a nucleic acid molecule can be chemically synthesized in one piece, or in several pieces, by automated synthesis methods known in the art. The complementary strand can likewise be synthesized in one or more pieces, and a double-stranded molecule made by annealing the complementary strands. Direct synthesis is particularly advantageous for producing relatively short molecules, such as oligonucleotide probes and primers, and nucleic acid molecules containing modified nucleotides or linkages.

The invention also provides a vector containing an isolated PFM nucleic acid molecule. The vectors of the invention are useful for subcloning and amplifying an isolated PFM nucleic acid molecule, and for recombinantly expressing a PFM polypeptide. A vector of the invention can include a variety of elements useful for cloning and/or expression of PFM nucleic acid molecules, such as enhancer sequences and promoter sequences from a viral, bacterial or mammalian gene, which provide for constitutive, inducible or cell-specific RNA transcription; transcription termination and RNA processing signals, including polyadenylation signals, which provide for stability of a transcribed mRNA sequence; an origin of replication, which allows for proper episomal replication; selectable marker genes, such as a neomycin or hygromycin resistance gene, useful for selecting stable or transient transfectants in mammalian cells, or an ampicillan resistance gene, useful for selecting transformants in prokaryotic cells; and versatile multiple cloning sites for inserting nucleic acid molecules of interest.

Cloning vectors of the invention include, for example, viral vectors such as a bacteriophage, a baculovirus or a retrovirus; cosmids or plasmids; and, particularly for cloning large nucleic acid molecules, bacterial artificial chromosome vectors (BACs) and yeast artificial chromosome vectors (YACs). Such vectors are commercially available, and their uses are well known in the art.

If it is desired to express PFM RNA transcripts or polypeptides, a PFM nucleic acid molecule can be inserted into an expression vector such that it is operatively linked to a promoter of RNA transcription. The term “operatively linked,” as used herein, is intended to mean that the nucleic acid molecule is positioned with respect to a PFM promoter, or heterologous promoter, in such a manner that the promoter will direct the transcription of RNA using the nucleic acid molecule as a template. Methods for operatively linking a nucleic acid to a desired promoter are well known in the art and include, for example, cloning the nucleic acid into a vector containing the desired promoter, or appending the promoter to a nucleic acid sequence using PCR. Thus, an expression vector containing a PFM nucleic acid molecule operatively linked to a promoter of RNA transcription can be used to express PFM transcripts and polypeptides in a desired host cell, or in an in vitro system, such as an extract or lysate that supports transcription and translation. Contemplated expression vectors include vectors containing regulatory sequences known in the art to provide for expression in bacterial cells, yeast cells, insect cells, mammalian cells and other vertebrate cells.

A variety of expression vectors are commercially available, and can be further modified, if desired, to include appropriate regulatory elements to provide for the desired level of expression or replication in the host cell. For example, appropriate promoter and enhancer elements can be chosen to provide for constitutive, inducible or cell type-specific expression. Useful constitutive promoter and enhancer elements for expression of PFM in mammalian cells include, for example, RSV, CMV, SV40 and IgH elements. An exemplary inducible expression element is a steroid response element, while an exemplary cell-specific expression element is a prostate specific antigen (PSA) regulatory sequence. Other constitutive, inducible and cell type-specific regulatory elements are well known in the art.

Exemplary host cells that can be used to express recombinant PFM molecules include mammalian primary cells; established mammalian cell lines, such as COS, CHO, HeLa, NIH3T3, HEK 293-T and PC12 cells; amphibian cells, such as Xenopus embryos and oocytes; and other vertebrate cells. Exemplary host cells also include insect cells (e.g. Drosophila), yeast cells (e.g. S. cerevisiae, S. pombe, or Pichia pastoris) and prokaryotic cells (e.g. E. coli).

Methods for introducing a cloning or expression vector into a host cell are well known in the art and include, for example, various methods of transfection such as calcium phosphate, DEAE-dextran and lipofection methods, viral transduction, electroporation and microinjection. Host cells expressing PFM nucleic acid molecules can be used, for example, as a source to isolate recombinantly expressed PFM polypeptides, to identify and isolate molecules that regulate or interact with PFM nucleic acids and polypeptides, or to screen for compounds that enhance or inhibit the activity of a PFM molecule of the invention, as described further below.

The methods of isolating, cloning and expressing nucleic acid molecules of the invention referred to herein are routine in the art and are described in detail, for example, in Sambrook et al., Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratory, New York (1992) and in Ansubel et al., Current Protocols in Molecular Biology, John Wiley and Sons, Baltimore, Md. (1998), which are incorporated herein by reference.

PFM Polypeptides

The invention also provides isolated PFM polypeptides. The isolated PFM polypeptides of the invention can be used in a variety of diagnostic and therapeutic applications. For example, as described in more detail below, the isolated PFM polypeptides can be used to generate antibodies that can be used as reagents to detect PFM expression in a sample, or in screening methods to identify compounds and cellular molecules that bind PFM and modulate cell proliferation.

In one embodiment, the invention provides an isolated polypeptide, containing a PFM PR domain amino acid sequence selected from the group consisting of SEQ ID NOS:18, 20, 22, 24, 26 and 28. In another embodiment, the invention provides an isolated polypeptide, containing a PFM ZF domain amino acid sequence selected from the group consisting of SEQ ID NOS:64, 66, 68, 70, 72, 74 and 76. Also provided are modifications of these polypeptides that are immunologically equivalent thereto, or that have at least 60% identity thereto.

Exemplary isolated polypeptides provided by the invention that contain a PFM PR domain or that contain a PFM ZF domain are polypeptides having the sequence of SEQ ID NOS:2, 4, 6, 8, 10, 12, 14 or 16, or are immunologically equivalent modifications thereof.

Other isolated polypeptides provided by the invention contain both the PR domain and ZF domain of a PFM, as set forth above, and, optionally, contain PFM amino acid sequences between the PR domain and ZF domain.

The term “isolated,” in reference to a PFM polypeptide of the invention, is intended to mean that the molecule is substantially removed or separated from components with which it is naturally associated, or otherwise modified by the hand of man. Thus, the term “isolated PFM polypeptide” excludes PFM polypeptides as they exist in nature.

As used herein, the term “immunologically equivalent,” in reference to a PFM polypeptide of the invention, refers to an amino acid sequence that is capable of being recognized by an antibody that also specifically binds to the reference PFM sequence. The term “specifically binds,” as used herein, refers to binding with high affinity to the subject polypeptide, and binding with substantially lower affinity to an unrelated polypeptide, such as bovine serum albumin. High affinity binding includes binding with a dissociation constant (Kd) of less than about 10⁻⁶ M, preferably less than about 10⁻⁷ M, such as less than about 10⁻⁸ M. Methods of determining binding affinity are well known in the art and are described, for example, in Harlow and Lane, Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory, New York (1989).

In general, an amino acid sequence that is immunologically equivalent to a PFM polypeptide of the invention will have greater than about 60% identity, such as greater than about 70% identity, preferably greater than about 80% identity to the reference sequence. Identity of any two amino acid sequences can be determined by those skilled in the art based, for example, on a BLAST 2.0 computer alignment, using default parameters.

Those skilled in the art understand that two polypeptides with a high percentage of identity over the entire sequence, or over a substantial portion of the sequence, are more likely to exhibit similar biological activities than two molecules with the same percentage identity over a shorter portion of the sequence. Furthermore, two polypeptides that fold into common epitope structures are also more likely to exhibit similar biological activities than two molecules that do not share a common three-dimensional structure. Accordingly, an amino acid sequence that is “immunologically equivalent” to a PFM polypeptide can further be “biologically equivalent” to a PFM polypeptide.

As used herein, the term “biologically equivalent” is intended to indicate that the polypeptide has one or more of the biological properties characteristic of the reference polypeptide. As disclosed herein, biological properties characteristic of PFM polypeptides include, for example, growth modulating activity, regulation of chromatin-mediated gene expression, specific binding to cellular proteins and specific binding to DNA.

Thus, a polypeptide that is a “modification” of a reference amino acid sequence can include one or more additions, deletions or substitutions with respect to the reference sequence. In particular, a modification can include a conservative substitution, such as substitution of an apolar amino acid with another apolar amino acid (such as replacement of leucine with isoleucine), or substitution of a charged amino acid with a similarly charged amino acid (such as replacement of a glutamic acid with an aspartic acid). A modification can also include a nonconservative change, wherein a substituted amino acid has different but sufficiently similar structural or chemical properties that permits such a substitution without adversely affecting the desired immunological or biological activity.

A “modification” of a reference amino acid sequence that is “immunologically equivalent” or “biologically equivalent” to the reference amino acid sequence can also be a chemical or enzymatic modification, including but not limited to replacement of hydrogen by an alkyl, acyl, or amino group; esterification of a carboxyl group with a suitable alkyl or aryl moiety; alkylation of a hydroxyl group to form an ether derivative; phosphorylation or dephosphorylation of a serine, threonine or tyrosine residue; or N- or O-linked glycosylation.

Exemplary “modifications” of the recited PFM sequences include sequences that correspond to homologs of other species, such as primates, mouse, rat, rabbit, bovine, porcine, ovine, canine or feline species. Furthermore, exemplary “modifications” of the recited PFM can correspond to splice variant forms, or internal translation products, of recited PFM sequences. Thus, for example, a modification of a PFM polypeptide of the invention can lack one or more of the A, B or C boxes of the PR domain.

Those skilled in the art can determine appropriate amino acid modifications for a given application. For example, a modification can serve to increase the stability, bioavailability, bioactiviy or immunogenicity of the polypeptide, or to facilitate its purification. Thus, introduction of a D-amino acid or an amino acid analog for its corresponding L-amino acid, or deletion of a lysine residue, can stabilize a polypeptide and reduce degradation. Addition of tag sequences, such as epitope tags, histidine tags, glutathione-S-transferase (GST) and the like, or addition of sorting sequences, can facilitate purification of a recombinant polypeptide. Addition of carrier sequences, such as keyhole lympet hemocyanin, can enhance recognition of the polypeptide by the immune system. Depending on the modification and the source of the polypeptide, the modification can be introduced into the polypeptide, or into the encoding nucleic acid sequence.

Computer programs known in the art can provide guidance in determining which amino acid residues can be modified as indicated above without abolishing the immunological activity or a desired biological activity of a PFM polypeptide (see, for example, Eroshkin et al., Comput. Appl. Biosci. 9:491-497 (1993)). Additionally, guidance in modifying amino acid sequences while retaining functional activity is provided by aligning homologous PFM polypeptides from various species. Those skilled in the art understand that evolutionarily conserved amino acid residues and domains are more likely to be important for maintaining biological activity than less well-conserved residues and domains.

In yet another embodiment, the invention provides an isolated PFM peptide, having at least 8 contiguous amino acids of SEQ ID NOS:2, 4, 6, 8, 10, 12, 14 or 16. As used herein, the term “PFM peptide” refers to a peptide having at least 8 contiguous amino acids of PFM, such as at least 10, 12, 15, 20 or 25 contiguous amino acids, preferably at least 30, 40 or 50 contiguous amino acids of PFM, up to the full-length protein minus one amino acid.

A peptide of such size contains at least one epitope specific to PFM, and can thus be used as an immunogen to produce PFM-specific antibodies, or as an antigen to purify PFM antibodies. PFM peptides that are likely to be antigenic or immunogenic can be predicted using methods and algorithms known in the art and described, for example, by Irnaten et al., Protein Eng. 11:949-955 (1998), and Savoie et al., Pac. Symp. Biocomput. 1999:182-189 (1999). Immunogenicity of the PFM peptides of the invention can be determined by methods known in the art, such as assay of a delayed-type hypersensitivity response in an animal sensitized to a PFM polypeptide, or by elicitation of PFM specific antibodies. Likewise, antigenicity of the PFM peptides of the invention can be determined by methods known in the art, such as by ELISA analysis, as described, for example, in Harlow and Lane, supra (1988).

The PFM peptides of the invention can also be used in screening methods to identify PFM-binding cellular molecules and modulatory compounds, as described further below.

In one embodiment, the invention provides PFM peptides having an amino acid sequence of an A, B or C box of a PFM PR domain. Thus, the invention provides PFM peptides selected from the group consisting of SEQ ID NOS:30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60 and 62.

In another embodiment, the invention provides PFM peptides that contain an amino acid sequence of a PFM ZF domain zinc finger motif. The PFM zinc finger motifs are underlined in FIGS. 1B, 2B, 3B, 4B, 5B, 7B and 8B.

In yet another embodiment, the invention provides isolated PFM peptides that contain at least part of the amino acid sequence of the PKZL domain of PFM4, which is amino acids 207-306 of the sequence shown in FIG. 7B.

In a further embodiment, the invention provides isolated PFM peptides that contain the amino acid sequence of the LXCXE motif of PFM2 or mPFM2. Thus, the invention provides PFM peptides containing an amino acid sequence selected from the group consisting of SEQ ID NOS:89 and 91, such as containing the amino acid sequence DRLGCKEDY (SEQ ID NO:92) or the amino acid sequence GHLGCEEDF (SEQ ID NO:93).

The isolated PFM polypeptides and peptides of the invention can be prepared by methods known in the art, including biochemical, recombinant and synthetic methods. For example, PFM can be purified by routine biochemical methods from a cell or tissue source that expresses abundant amounts of the corresponding transcript or polypeptide. The diagnostic methods disclosed herein can be adapted for determining which cells and tissues, and which subcellular fractions therefrom, are appropriate starting materials. Biochemical purification can include, for example, steps such as solubilization of the appropriate tissue or cells, isolation of desired subcellular fractions, size or affinity chromatography, electrophoresis, and immunoaffinity procedures. The methods and conditions for biochemical purification of a polypeptide of the invention can be chosen by those skilled in the art, and purification monitored, for example, by an ELISA assay or a functional assay, such as a DNA-binding or protein-binding assay.

A PFM polypeptide or peptide having any desired boundaries, and a polypeptide having a modification to the native PFM amino acid sequences, can also be produced by recombinant methods. Recombinant methods involve expressing a nucleic acid molecule encoding the desired polypeptide or fragment in a host cell or cell extract, and isolating the recombinant polypeptide or fragment, such as by routine biochemical purification methods described above. To facilitate identification and purification of the recombinant polypeptide, it is often desirable to insert or add, in-frame with the coding sequence, nucleic acid sequences that encode epitope tags, polyhistidine tags, glutathione-S-transferase (GST) domains, and similar affinity binding sequences, or sequences that direct expression of the polypeptide in the periplasm or direct secretion. Methods for producing and expressing recombinant polypeptides in vitro and in prokaryotic and eukaryotic host cells are well known in the art.

Thus, the invention provides a method of isolating PFM polypeptide, by growing a host cell containing an expression vector encoding PFM polypeptide, under conditions appropriate for expression of the encoded PFM polypeptide, and isolating the PFM polypeptide.

The PFM polypeptide fragments and peptides of the invenition can also be produced, for example, by enzymatic or chemical cleavage of the full-length polypeptide. Methods for enzymatic and chemical cleavage and for purification of the resultant peptide fragments are well known in the art (see, for example, Deutscher, Methods in Enzymology, Vol. 182, “Guide to Protein Purification,” San Diego: Academic Press, Inc. (1990), which is incorporated herein by reference).

Furthermore, PFM polypeptides and peptides can be produced by chemical synthesis. If desired, such as to optimize their functional activity, stability or bioavailability, such molecules can be modified to include D-stereoisomers, non-naturally occurring amino acids, and amino acid analogs and mimetics. Examples of modified amino acids and their uses are presented in Sawyer, Peptide Based Drug Design, ACS, Washington (1995) and Gross and Meienhofer, The Peptides: Analysis, Synthesis, Biology, Academic Press, Inc., New York (1983), both of which are incorporated herein by reference.

PFM Antibodies

The invention also provides an antibody or antigen binding fragment thereof which specifically binds a PFM polypeptide. Such antibodies can be used, for example, to affinity purify a PFM polypeptide from a cell or tissue source, or in therapeutic and diagnostic applications described below.

An “antigen binding fragment” of an antibody of the invention includes, for example, individual heavy or light chains and fragments thereof, such as VL, VH and Fd; monovalent fragments, such as Fv, Fab, and Fab′; bivalent fragments such as F(ab′)₂; single chain Fv (scFv); and Fc fragments. Antigen binding fragments include, for example, fragments produced by protease digestion or reduction of an antibody, as well as fragments produced by recombinant DNA methods known to those skilled in the art.

The antibodies of the invention can be produced by any method known in the art. For example, a PFM polypeptide or immunogenic peptide of the invention, or a nucleic acid expressing such a polypeptide, can be administered to an animal, using standard methods, and polyclonal antibodies isolated therefrom. Such polypeptides of peptides, if desired, can be conjugated to a carrier, such as KLH, serum albumin, tetanus toxoid and the like, using standard linking techniques, to increase their immunogenicity. Additionally, such peptides can be formulated together with an adjuvant known in the art, such as Freund's complete or incomplete adjuvant. The antibodies so generated can be used in the form of serum isolated from an immunized animal, or the antibody can be affinity purified from the serum using PFM peptides or polypeptides.

Additionally, the PFM antibodies of the invention can be monoclonal antibodies produced by a hybridoma cell line, by chemical synthesis, or by recombinant methods. Modified antibodies, such as chimeric antibodies, humanized antibodies and CDR-grafted or bifunctional antibodies, can also be produced by methods well known to those skilled in the art.

Methods of preparing and using antibodies and antigen-binding fragments, including detectably labeled antibodies, are described, for example, in Harlow and Lane, Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory, New York (1989); in Day, E. D., Advanced Immunochemistry, Second Ed., Wiley-Liss, Inc., New York, N.Y. (1990); and in Borrebaeck (Ed.), Antibody Engineering, Second Ed., Oxford University Press, New York (1995), which are incorporated herein by reference.

PFM Modulatory Compounds

The invention also provides methods of identifying cellular and non-cellular molecules that modulate PFM expression and activity. These molecules can be used in ex vivo and in vivo therapeutic applications, as described further below, to promote or inhibit cell proliferation.

As disclosed herein, the PR domain of the PFM polypeptides of the invention functions as a specific protein binding domain. By specifically binding particular cellular proteins, the intact PR domain contributes to the function of PFM polypeptide as a suppressor of cell growth. Likewise, the LXCXE motif is known to bind RB and likely to bind other cellular proteins. The PKZL domain is also likely to bind cellular proteins. Thus, an isolated PFM polypeptide of the invention containing a PR domain, and LXCXE motif or a PKZL domain can be used, for example, in binding assays to identify cellular proteins that normally bind PFM.

Such cellular proteins are themselves likely to have positive or negative growth modulating activity and are also appropriate targets for therapeutic intervention to prevent or treat proliferative disorders. Furthermore, peptides or analogs corresponding to the PFM binding interface of such cellular proteins, or of PFM, can be administered as therapeutic compounds to specifically interfere with PFM function.

Various binding assays to identify cellular proteins that interact with protein binding domains are known in the art and include, for example, yeast two-hybrid screening assays (see, for example, Luban et al., Curr. Opin. Biotechnol. 6:59-64 (1995)) and affinity column chromatography methods using cellular extracts. By synthesizing or expressing polypeptide fragments containing various PFM sequences or deletions, the PFM binding interface can be readily identified.

As further disclosed herein, the zinc finger (ZF) domain of the PFM polypeptides of the invention functions as a specific DNA binding domain. By specifically binding particular DNA sequences, the ZF domain contributes to the function of PFM polypeptide as a suppressor of cell growth. Thus, an isolated PFM polypeptide of the invention containing a ZF domain, or one or more ZF motifs therefrom, can be used, for example, in binding assays to identify cellular DNA sequences that normally bind PFM. Such cellular DNA sequences are likely to be regulatory sequences for genes which themselves have positive or negative growth modulating activity, and which are appropriate targets for therapeutic invervention to prevent or treat proliferative disorders. Furthermore, oligonucleotides or analogs corresponding the PFM binding DNA sequences, can be administered as therapeutic compounds to specifically interfere with PFM function. Additionally, the ZF domain, or one or more ZF motifs therefrom, can be administered as therapeutic compounds to specifically interfere with PFM function.

Various assays to identify DNA sequences that bind DNA binding domains are known in the art and include, for example, Cyclic Amplification and Selection of Targets (CASTing), as described by Wright et al., Mol. Cell. Biol. 11:4104-4110 (1991), and the Multiplex Selection Technique (MuST), as described by Nallur et al., Proc. Natl. Acad. Sci. USA 93:1184-1189 (1996).

The invention also provides a method of identifying non-cellular molecules, or “PFM modulatory compounds,” that modulate PFM expression or activity. As used herein, the term “PFM modulatory compound” refers to a molecule that specifically binds a PFM nucleic acid molecule or PFM polypeptide and alters its expression or activity. A PFM modulatory compound can be a Naturally occurring macromolecule, such as a peptide, nucleic acid, carbohydrate, lipid, or any combination thereof. A PFM modulatory compound also can be a partially or completely synthetic derivative, analog or mimetic of such a macromolecule, or a small organic or inorganic molecule prepared partly or completely by combinatorial chemistry methods.

Methods for producing pluralities of compounds to use in screening for PFM modulatory compounds, including chemical or biological molecules such as simple or complex organic molecules, metal-containing compounds, carbohydrates, peptides, proteins, peptidomimetics, glycoproteins, lipoproteins, nucleic acids, antibodies, and the like, are well known in the art and are described, for example, in Huse, U.S. Pat. No. 5,264,563; Francis et al., Curr. Opin. Chem. Biol. 2:422-428 (1998); Tietze et al., Curr. Biol., 2:363-371 (1998); Sofia, Mol. Divers. 3:75-94 (1998); Eichler et al., Med. Res. Rev. 15:481-496 (1995); and the like. Libraries containing large numbers of natural and synthetic compounds also can be obtained from commercial sources.

A variety of low- and high-throughput assays known in the art are suitable for detecting specific binding interactions between a PFM nucleic acid molecule or polypeptide and a candidate PFM modulatory compound. Both direct and competitive assays can be performed, including, for example, fluorescence correlation spectroscopy (FCS) and scintillation proximity assays (SPA) reviewed in Major, J. Receptor and Signal Transduction Res. 15:595-607 (1995); and in Sterrer et al., J. Receptor and Signal Transduction Res. 17:511-520 (1997)). Other assays for detecting specific binding interactions include, for example, ELISA assays, FACS analysis, and affinity separation methods, which are described, for example, in Harlow and Lane, Eds., Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory (1988).

Assays to identify compounds that modulate PFM gene expression can involve first transducing cells with a PFM promoter-reporter nucleic acid construct such that a change in expression of a protein such as β-lactamase, luciferase, green fluorescent protein or β-galactosidase will be detected in response to contacting the cell with a PFM modulatory compound that upregulates or downregulates expression of PFM. Such assays and reporter systems are well known in the art and are described, for example, at www.aurorabio.com/tech_platform-assay_technologies.html (visited Aug. 5, 1999). Other assays to identify compounds that modulate PFM gene expression include assays that measure levels of PFM transcripts, such as Northern blots, RNase protection assays, and RT-PCR.

Assays to identify compounds that modulate PFM polypeptide expression can involve detecting a change in PFM polypeptide abundance in response to contacting the cell with a PFM modulatory compound. Assays for detecting changes in polypeptide expression include, for example, immunoassays with specific PFM antibodies, such as immunofluorescence, immunohistochemistry and immunoprecipitation assays.

Appropriate assays to determine whether a PFM modulatory compound affects PFM activity so as to inhibit or promote cell proliferation, can be determined by those skilled in the art. The skilled artisan appreciates that molecular pathways involved in cell proliferation are generally well conserved among eukaryotic organisms. Therefore, a proliferation assay can be performed in any eukaryotic cell type in which altered proliferation can be detected including, for example, primary mammalian cells, normal and transformed mammalian cell lines, yeast, insect cells and amphibian cells.

A molecule that modulates cell proliferation can, for example, cause cell cycle arrest at a particular stage of mitosis or meiosis, induce or prevent apoptosis, or promote progression through the cell cycle when normal cells would arrest. Such qualitative changes in the cell cycle can be determined by methods known in the art, and which depend on the cell type used in the assay. A molecule that modulates cell proliferation can also, for example, cause faster or slower progression through the cell cycle, resulting in an increased or decreased number of cells in the population after a given period of time. Those skilled in the art can choose an appropriate assay to determine whether, and by what mechanism, a molecule of the invention affects cell proliferation.

A molecule that modulates cell proliferation can also restore more normal proliferative characteristics to a neoplastic cell. Such a molecule can advantageously be used in therapeutic applications to prevent or treat cancer. To determine whether a molecule of the invention restores more normal proliferative characteristics on a neoplastic cell, an assay can be performed in a mammalian cell that exhibits neoplastic proliferative characteristics, such as soft agar colony formation, overgrowth of a cell monolayer, proliferation in low serum, abnormally rapid proliferation, or tumor formation in an animal. Such cells are known in the art and include both tumor cell lines and primary tumor cells. A molecule of the invention can be introduced or expressed in such a cell, and a determination can be made whether the molecule restores more normal proliferative characteristics to the cell, such as slower growth in culture, fewer foci, fewer soft agar colonies, or a reduction in tumor size, as compared to the parental cell.

Therapeutic Applications

As disclosed herein, PFM nucleic acid molecules encoding PFM polypeptides with intact PR domains inhibit cell growth. In contrast, PFM nucleic acid molecules encoding PFM polypeptides with partial PR domains, or lacking PR domains, promote cell growth. Thus, by selectively manipulating the expression or activity of either the PR+ or PR− forms of the PFM molecules of the invention, or both, it is readily apparent that cell growth can be modulated in either a positive or negative manner, as desired.

Accordingly, the invention provides PFM molecules and therapeutic methods that can be used to inhibit the growth of cells in culture, or in a subject. Advantageously, the molecules and therapeutic methods can be used to treat proliferative disorders in a subject. As used herein, the term “proliferative disorder” refers to a condition in which unwanted cell proliferation of one or more subset of cells in a mammal, such as a human, occurs, resulting in harm (e.g., discomfort or decreased life expectancy) to the mammal. Cell proliferative disorders include diseases such as cancer, in which the cells are neoplastically transformed, but also include diseases resulting from overgrowth of normal cells. For example, cell proliferative disorders include diseases associated with the overgrowth of connective tissues, such as various fibrotic diseases, including scleroderma, arthritis, alcoholic liver cirrhosis, keloid, and hypertropic scarring; vascular proliferative disorders, such as atherosclerosis; and benign tumors.

The invention also provides PFM molecules and therapeutic methods that can be used to enhance proliferation of normal cells. For some therapeutic applications, it may be useful to increase the proliferation of normal cells, without rendering the cells cancerous. In particular, in diseases of cell degeneration, such as Duchenne's muscular dystrophy, insulin-dependent diabetes mellitus, Parkinson's disease, Huntington's disease, Alzheimer's disease, paralysis, cerebellar atrophy, and the like, it may be useful to remove some of the remaining normal cells from the affected tissue of the individual, and culture the cells in large numbers ex vivo for reimplantation into the patient. Additionally, in applications such as wound healing and skin grafts, it is often desirable to increase the proliferation of normal cells.

In one embodiment, the invention provides a method for modulating cell growth, by introducing a vector containing an isolated PFM1, hPFM2, mPFM2, PFM3, PFM4 or PFM5 nucleic acid molecule of the invention, operatively linked to a promoter of RNA expression, into a host cell, and expressing the encoded PFM polypeptide in an amount effective to modulate growth of the cell. For applications in which inhibition of cell growth is desirable, expression vectors containing isolated full-length PFM nucleic acid molecules, or modifications of full-length PFM nucleic acid molecules that retain the growth inhibitory activity of PFM, can be introduced into cells under conditions in which the PFM polypeptide is expressed in an effective amount to inhibit cell proliferation. For applications in which promotion of cell growth is desirable, expression vectors which contain portions of the PFM nucleic acid molecules that compete with PFM for substrates or effectors, such as the PR domain or zinc finger domain, or both, can be introduced into cells under conditions in which the PFM polypeptide is expressed in an effective amount to promote cell proliferation.

Useful mammalian expression vectors for such therapeutic applications, and methods of introducing such vectors into mammalian cells either ex vivo or in vivo, for expression of the encoded polypeptide, are well known in the art. For example, a plasmid expression vector can be introduced into a cell by calcium-phosphate mediated transfection, DEAE-Dextran-mediated transfection, lipofection, polybrene- or polylysine-mediated transfection, electroporation, or by conjugation to an antibody, gramacidin S, artificial viral envelopes or other intracellular carriers. A viral expression vector can be introduced into a cell in an expressible form by infection or transduction, for example, or by encapsulation in a liposome. Appropriate viral vectors for gene therapy applications are well known in the art and include, for example, retroviruses, adenoviruses, adeno-associated viruses and herpes virus.

In another embodiment, the invention provides a method for modulating cell growth by introducing into a cell an effective amount of an antisense oligonucleotide or a ribozyme that inhibits expression of PFM, thereby modulating growth of the cell. Methods for modulating gene expression using antisense oligonucleotides and ribozymes are also well known in the art. Thus, an antisense molecule or ribozyme that selectively inhibits expression of the PR−, growth promoting form of PFM, can be used to inhibit cell proliferation. In contrast, an antisense molecule or ribozyme that selectively inhibits expression of the PR+, growth suppressing form of PFM, can be used to promote cell proliferation.

Antisense oligonucleotides that inhibit PFM gene expression generally are from about 15 to about 30 nucleotides in length, and often include sequences found within the first 30 nucleotides of the transcript being targeted. The preparation and use of antisense oligonucleotides are well known in the art and described in detail, for example, in Cohen (ed), Oligonucleotides: Antisense Inhibitors of Gene Expression, CRC Press Inc., Boca Raton (1989). Likewise, methods of preparing and using hairpin and hammerhead ribozymes for the selective inhibition of gene expression are known in the art and are described, for example, in Poeschla et al., Curr. Opin. Oncol. 6:601-606 (1994).

In a further embodiment, the invention provides a method for modulating cell growth by contacting the cell with an effective amount of a PEM modulatory compound. Methods of identifying PFM modulatory compounds have been described above.

In yet another embodiment, the invention provides a method for modulating cell growth by administering antibodies that specifically bind PFM. For example, antibodies that selectively detect a growth promoting structural variant of PFM, such as the PR− form of PFM polypeptide, can be administered to selectively target cells that express this variant. If desired, such antibodies can be administered in conjuction with a cytotoxic or cytostatic moiety, such as a radioisotope or toxin, in order to neutralize or kill cells expressing the desired structural variant.

The PFM therapeutic molecules of the invention described herein, including expression vectors, antisense oligonucleotides and ribozymes, PFM modulatory compounds, and antibodies, can optionally be formulated together with a pharmaceutically acceptable carrier for delivery to a cultured cell or to a subject. Suitable pharmaceutically accepable carriers are well known in the art and include, for example, aqueous or organic solvents such as physiologically buffered saline, glycols, glycerol, oils or injectable organic esters. A pharmaceutically acceptable carrier can also contain a physiologically acceptable compound that acts, for example, to stabilize or increase the solubility of a pharmaceutical composition. Such a physiologically acceptable compound can be, for example, a carbohydrate, such as glucose, sucrose or dextrans; an antioxidant, such as ascorbic acid or glutathione; a chelating agent; a low molecular weight protein; or another stabilizer or excipient. Pharmaceutically acceptable carriers, including solvents, stabilizers, solubilizers and preservatives, are described, for example, in Martin, Remington's Pharm. Sci., 15th Ed. (Mack Publ. Co., Easton, 1975).

Those skilled in the art can formulate the therapeutic molecules to ensure proper distribution in vivo. For example, the blood-brain barrier (BBB) excludes many highly hydrophilic compounds. To ensure that the therapeutic molecules of the invention cross the BBB, if desired, they can be formulated, for example, in liposomes, or chemically derivatized. Methods of ensuring appropriate distribution in vivo can also be provided by rechargable or biodegradable devices, particularly where gradients of concentrations of drug in a tissue are desired. Various slow release polymeric devices are known in the art for the controlled delivery of drugs, and include both biodegradable and non-degradable polymers and hydrogels. Those skilled in the art understand that the choice of the pharmaceutical formulation and the appropriate preparation of the composition will depend on the intended use and mode of administration.

The PFM therapeutic molecules of the invention, including expression vectors, antisense oligonucleotides and ribozymes, PFM modulatory compounds, and antibodies, can be administered to a subject by any effective route. Suitable routes for delivering the therapeutic molecules of the invention include topically, intraocularly, intradermally, parenterally, orally, intranasally, intravenously, intramuscularly, intraspinally, intracerebrally and subcutaneously. In a preferred embodiment, the therapeutic PFM molecules are directly injected into a solid tumor, tumor-containing organ or tumor containing body cavity, in a effective amount to inhibit proliferation of the tumor cells. Alternatively, the therapeutic PFM molecules of the invention can be administered systemically into the blood or lymphatic circulation to reach cells in the circulatory system or in any organ or tissue.

An effective dose of a therapeutic molecule of the invention can be determined, for example, by extrapolation from the concentration required for binding an isolated PFM nucleic acid or polypeptide in the binding assays described herein; from the dose required to modulate PFM nucleic acid or polypeptide expression in the expression assays described herein; or from the dose required to modulate cell proliferation in the proliferation assays described herein.

An effective dose of a molecule of the invention for the treatment of proliferative disorders can also be determined from appropriate animal models, such as xenografts of human tumors in rats or mice. Human cancer cells can be introduced into an animal by a number of routes, including subcutaneously, intraveneously and intraperitoneally. Following establishment of a tumor, the animals can be treated with different doses of a molecule of the invention, and tumor mass or volume can be determined. An effective dose for treating cancer is a dose that results in either partial or complete regression of the tumor, reduction in metastasis, reduced discomfort, or prolonged lifespan.

The appropriate dose for treatment of a human subject with a therapeutic molecule of the invention can be determined by those skilled in the art, and is dependent on the nature and bioactivity of the particular compound, the desired route of administration, the gender, age and health of the individual, the number of doses and duration of treatment, and the particular condition being treated.

Diagnostic Applications

The PFM nucleic acids and polypeptides disclosed herein exist in different forms, depending on the splice variant expressed. PFM nucleic acids and polypeptides that express or contain an intact PR domain (PR+) are associated with regulated, or normal, cell proliferation. A decrease in the total amount, or relative amount, of the PR+ form of a PFM, or an increase in the total amount, or relative amount, of the PR− form of a PFM, is associated with unregulated, or pathological, cell proliferation. Therefore, determining the total or relative abundance of the. PR+ and PR− forms of PFM, or identifying alterations in the expression or structure of PFM nucleic acid molecules or polypeptides, can be used to distinguish between normal and pathologically proliferative cells in a sample.

The invention thus provides methods of detecting PFM nucleic acids and polypeptides in a sample. As used herein, the term “sample” is intended to mean any biological fluid, cell, tissue, organ or portion thereof, that includes or potentially includes PFM nucleic acids or polypeptides. The term includes samples present in an individual as well as samples obtained or derived from the individual. For example, a sample can be a histologic section of a specimen obtained by biopsy, or cells that are placed in or adapted to tissue culture. A sample further can be a subcellular fraction or extract, or a crude or substantially pure nucleic acid or protein preparation. A sample can be prepared by methods known in the art suitable for the particular format of the detection method employed.

The detection methods of the invention can advantageously be used, for example, to identify pathologically proliferative cells, such as neoplastic cells, in a sample. As used herein, the term “neoplastic cell” is intended to mean a cell that exhibits histological or proliferative features of a malignant or premalignant cell. For example, by histological methods, a neoplastic cell can be observed to invade into surrounding normal tissue, have an increased mitotic index, an increased nuclear to cytoplasmic ratio, altered deposition of extracellular matrix, or a less differentiated phenotype. A neoplastic cell can also exhibit unregulated proliferation, such as anchorage independent cell growth, proliferation in reduced-serum medium, loss of contact inhibition, or rapid proliferation compared to normal cells. The diagnostic methods described herein are applicable to the identification of any type of neoplastic cell, such as neoplastic cells present in solid tumors (carcinomas and sarcomas) such as breast, colorectal, gynecological, lung, prostate, bladder, renal, liver, urethral, endocrinal, melanoma, basal cell, central nervous system, lymphoma, stomach, esophageal, squamous cell cancers, as well as all forms of leukemias, and metastases therefrom.

The diagnostic methods described herein can also be adapted for use as prognostic assays. Such an application takes advantage of the observation that alterations in expression or structure of different tumor suppressor molecules take place at characteristic stages in the progression of a proliferative disease or of a tumor. Knowledge of the stage of the tumor allows the clinician to select the most appropriate treatment for the tumor and to predict the likelihood of success of that treatment.

The diagnostic methods described herein can also be used to identify individuals at increased risk of developing a proliferative disease, such as cancer, due to hereditary mutations in a PFM.

The invention thus provides methods for detecting PFM nucleic acid in a sample. In one embodiment, the method consists of contacting the sample with an isolated PFM1, mPFM2, hPFM2, PFM3, PFM4 or PFM5 nucleic acid molecule, under conditions that allow specific hybridization to PFM nucleic acid, and detecting specific hybridization. The method of the invention is exemplified in Examples I, II and V, below, in which detection of PFM nucleic acid in tissue samples is described.

In another embodiment, the method consists of contacting the sample with a PFM primer pair, under conditions that allow amplification of PFM nucleic acid, and detecting amplified PFM nucleic acid. The method of the invention is exemplified in Examples I, II, III and V, below, in which detection of PFM nucleic acid in tissue samples is described.

The methods of detecting PFM nucleic acid in a sample can be either qualitative or quantitative, as desired. For example, the presence, abundance, integrity or structure of a PFM, or of particular splice variants thereof, can be determined, as desired, depending on the assay format and the probe or primer pair chosen.

Useful assays for detecting PFM nucleic acid based on specific hybridization with an isolated PFM nucleic acid molecule are well known in the art and include, for example, in situ hybridization, which can be used to detect altered chromosomal location of the nucleic acid molecule, altered gene copy number, and RNA abundance, depending on the assay format used. Other hybridization assays include, for example, Northern blots and RNase protection assays, which can be used to determine the abundance and integrity of different RNA splice variants, and Southern blots, which can be used to determine the copy number and integrity of DNA. A PFM hybridization probe can be labeled with any suitable detectable moiety, such as a radioisotope, fluorochrome, chemiluminescent marker, biotin, or other detectable moiety known in the art that is detectable by analytical methods.

Useful assays for detecting PFM nucleic acid in a sample based on amplifying PFM nucleic acid with a PFM primer pair are also well known in the art, and include, for example, qualitative or quantitative polymerase chain reaction (PCR); reverse-transcription PCR (RT-PCR); SSCP analysis, which can readily identify a single point mutation in DNA, such as in a PCR or RT-PCR product; and coupled PCR, transcription and translation assays, such as the Protein Truncation Test, in which a mutation in DNA is determined by an altered protein product on an electrophoresis gel. Additionally, the amplified PFM nucleic acid can be sequenced to detect mutations and mutational hot-spots, and specific assays for large-scale screening of samples to identify such mutations can be developed.

The invention also provides methods for detecting PFM polypeptide in a sample, by contacting the sample with an agent specific for PFM, under conditions that allow specific binding of the agent to PFM polypeptide, and detecting the specifically bound agent. As used herein the term “agent specific for PFM” refers to a molecule that specifically binds PFM. An-example of a molecule that specifically binds PFM is a PFM antibody, or antigen binding fragment thereof. Additionally, the PFM binding and modulatory compounds identified in the affinity screening methods described above are also suitable agents that can be used in methods of detecting PFM polypeptides.

Assays for detecting PFM polypeptides include, for example, immunohistochemistry, immunofluorescence, ELISA assays, radioimmunoassay, Facs analysis, immunoprecipitation, and immunoblot analysis, using antibodies or antigen binding fragments specific for PFM. Various immunoassays are well known in the art, and can be readily modified by those skilled in the art in cases in which the agent is a PFM binding molecule other than an antibody. If desired, the agent or antibody can be rendered detectable by incorporation of, or by conjugation to, a detectable moiety, or binding to a secondary molecule that is itself detectably labeled.

In the detection methods of the invention, the nucleic acid probes or primers, and polypeptide binding agents, can advantageously be directed against the PR domain of PFM, or the A, B or C boxes thereof. Therefore, these assays can be used to distinguish between PR+ growth-inhibiting, and PR−, growth-promoting, forms of PFM in a sample.

The following examples are intended to illustrate but not limit the present invention.

EXAMPLE I Identification and Characterization of PFM1

This example shows identification of the gene encoding the PR-domain containing polypeptide designated PFM1, and characterization of its structure, expression pattern and chromosomal location.

cDNA libraries and EST databases were screened using the PR domain of RIZ1 as probe or query. This led to the identification of a mouse EST clone (mouse embryonic carcinoma cell line F9 cDNA clone B9H02, Accession Number D77868) encoding a PR domain. By sequence analysis of overlapping human cDNA clones obtained from the EST database and RACE, a contiguous full length cDNA sequence of 3.902 kb was identified (see FIG. 1A, SEQ ID NO:1), encoding an open reading frame of 796 amino acids from nt 139 to 2527 (see FIG. 1B, SEQ ID NO:2). The amino acid sequence is apparently full length because the ATG start codon at nucleotide 139 is preceded by an inframe stop codon. The predicted peptide sequence shows a PR domain in the middle portion of the protein followed by 6 zinc finger motifs at the carboxyl terminal half. The amino-terminal region did not show significant similarity to known genes and contains a Ser-rich region and a Pro-rich region. This gene was designated PFM1 for PR family member 1.

The structural features of PFM1 protein suggest a role for the protein as a DNA binding transcription factor. The PR domain of PFM1 is more related to BLIMP1 than to other PR genes. The location of the PR domain in the middle of the PFM1 protein is unusual in comparison with other PR family members, in which the PR domains of are located at the amino-terminus.

To determine the expression pattern of PFM1, Northern blot analysis was performed using either a 5′ probe or a non-overlapping 3′ probe of PFM1 cDNA (see FIG. 11A). Three different mRNA species were detected with the 5′ probe, whereas four mRNA species were detected with the 3′ probe (FIG. 11B, middle two panels). The major PFM1 mRNA species was ˜4.6 kb in size. The 4.6 kb species was observed in all human tissues tested but was significantly more abundant in ovary and testis (FIG. 11B). The relatively high levels of the housekeeping gene beta-actin mRNA in ovary may reflect its actual abundance or may indicate that a slightly higher amount of ovary mRNA was loaded (FIG. 11B, bottom panel). Even taking into account possible mRNA overloading, the level of PFM1 transcript in ovary was still higher than in other tissues, as was independently confirmed by RT-PCR analysis based on normalization to a different housekeeping gene, G3PDH (FIG. 11C).

Northern blot analysis using the 5′ probe also identified two alternative PFM1 mRNA species of ˜7.0 kb and ˜3.4 kb. The ˜7.0 kb transcript was specifically found in ovary and testis; the ˜3.4 kb transcript was found at low levels in peripheral blood leukocytes, colon, ovary, testis, prostate, and spleen (FIG. 11B, top two panels). All of these mRNA species were also detected with the 3′ probe (FIG. 11B, third panel from top). In addition, an mRNA species of ˜3.9 kb was specifically detected by the 3′ probe, most evidently in peripheral blood leukocytes but also visible in ovary and testis. Because this mRNA was not detected with the 5′ probe, which contains about 150 bp of the PR domain and all of the amino terminal regions (see FIG. 11A), this species likely represents a product of the PFM1 gene lacking the PR domain. Identification of a PR− PFM1 transcript reinforces previous observations that the expression of an alternative PR-lacking product appears to be a conserved feature of the PR domain gene family.

By RT-PCR analysis, eight other human tissue mRNAs were examined, in addition to those contained in the northern blot. Relatively high levels of PFM1 mRNA, similar to levels found in ovary and testis, were also observed in pancreas, prostate, placenta, heart, and brain (FIG. 11C). The lowest amount of PFM1 mRNA was found in skeletal muscle and liver. These data indicate that PFM1 gene is fairly ubiquitously expressed, but that the amount of expression varies in a tissue specific manner.

Obtaining the PFM1 cDNA sequence also allowed identification of an EST clone, gb|H33244 of PFM1 present in NGF treated PC-12 cells that was not present in non-treated PC-12 cells (Lee et al., Proc. Natl. Acad. Sci. USA 92:8303-8307 (1995)). This observation suggested that PFM1 expression may be higher in NGF-treated versus non-treated PC-12 cells. To test the effect of NGF on PFM1 expression, mRNA prepared from PC-12 cells that were in NGF-containing media for 9 days was used for RT-PCR analysis using primers derived from PFM cDNA sequences. The housekeeping gene beta-actin was amplified as a control for NGF non-responsive genes. As shown in FIG. 11D, NGF induced PFM1 gene expression between four- and eight-fold, indicating that PFM1 gene expression is induced upon neuronal cell differentiation. Therefore, PFM1 is likely to be involved in cell differentiation control and to play a role in the NGF signal transduction pathway.

Using PFM1 human cDNA as a query sequence, an STS (sequence tagged site) sequence, A005M11, of approximately 300 bp, which is identical to a portion of PFM1 sequence, was identified. This STS marker maps to between the markers D12S78 and D12S79 on human chromosome 12q (see Human Genome Resources at www.ncbi.nlm.nih.gov/genome/guide/). Several disease genes known to reside on 12q23-q24.1 have been mapped between D12S78 and D12S79, including SCA2 mutated in cerebellar ataxia (Gispert et al., Nature Genet. 4:295-299 (1993)), and ATP2A2 mutated in Darier disease (Sakuntabhai et al., Nature Genet. 21:271-277 (1999)). Based on the cytogenetic locations of these disease genes, it was concluded that PFM1 maps to 12q23-q24. 1 on the cytogenetic map.

The localization of PFM1 to human chromosome 12 was confirmed by analysis of somatic cell hybrids. PCR amplification of DNAs was performed, using a panel of human x rodent somatic cell hybrids, each retaining one intact human chromosome. A PCR fragment of PFM1 was only found in DNAs from the hybrid NA10868A, which contains chromosome 12.

Human chromosome band 12q23-q24.1 is thought to harbor tumor suppressor genes. Gene deletion or loss of heterozygosity in this region is found in several types of human cancers, including ovarian cancer (Hatta et al., Br. J. Cancer 75:1256-1262 (1997); Sato et al., Cancer Res. 51:5118-5122 (1991)), pancreatic cancer (Kimura et al., Cancer Res. 58:2456-2460 (1998)), and gastric cancer (Schmutte et al., Cancer Res. 57:3010-3015 (1997)). In addition, a gene involved in spinal muscular atrophies is thought to reside on 12q23-q24.1, which remains to be cloned (van der Vleuten et al., Eur. J. Hum. Genet. 6:376-382 (1998)).

Thus, because of the known involvement of PR-domain family members in cell differentiation and cancer, the chromosomal location of PFM1 suggests a role for PFM1 in human diseases including cancer and muscular atrophies. Furthermore, the specific high level expression of PFM1 in normal ovary and pancreas suggests that PFM1 is a particularly strong candidate for the ovarian and pancreatic cancer suppressor gene located on 12q23-q24.1.

EXAMPLE II Identification and Characterization of PFM2

This example shows identification of the gene encoding the PR-domain containing polypeptides designated PFM2 (human) and mPFM2 (mouse), and characterization of their structure, expression pattern and chromosomal location.

An EST sequence (1467290, Accession number AA884744) was identified that shows partial homology to the RIZ1 PR domain. Sequence analysis of this EST and other overlapping EST clones allowed the assembly of a contiguous cDNA sequence of 1.065 kb, designated PFM2 (FIG. 2A; SEQ ID NO:3). PFM2 cDNA encodes an open reading frame of 298 amino acids (FIG. 2B; SEQ ID NO:4). The predicted open reading frame of PFM2 contains the B and C boxes of the PR domain and six zinc finger domains (see FIG. 12A). The A box found in other PR-domain containing proteins was absent from the reading frame because of deletion of one nucleotide next to the B box region. This lack of one nucleotide has been confirmed by sequencing normal human genomic DNA.

Scanning of the peptide sequence also identified a LXCXE motif which is a sequence motif known to bind retinoblastoma protein. A similar motif is present in the RIZ gene products.

To analyze PFM2 gene expression, an MTN blot (Clontech) was probed with a 0.5 kb XbaI-NotI fragment from the plasmid 1467290, which corresponds to the N-terminal region of PFM2 immediately upstream of the zinc finger domain. Northern blot analysis identified abundant expression of PFM2 in the ovary (FIG. 12B). A major mRNA species of 6.0 kb and two alternative, less abundant transcripts of 8.0 and 4.0 kb were observed when using the PR domain region of PFM2 as a probe.

To further analyze PFM2 expression, MTC cDNAs (Clontech) were analyzed by PCR using primer PFM2.15 having the sequence 5′-GGTGAAAAGTTCGGACCCTTT-3′ (SEQ ID NO:81) and primer PFM2.18 having the sequence 5′-TGCCCGCTGTTGATTGTCTTC-3′ (SEQ ID NO:82). RT-PCR analysis of various human tissue RNAs confirmed that PFM2 expression is more abundant in ovary (FIG. 12C).

To map the chromosomal location of PFM2, the Standford TNG radiation hybrid panel was screened with a pair of PCR primers that amplify PFM2 gene. This mapped PFM2 to within 420 kb from the marker SHGC4-1184 on 4q25-4q26. The 4q25-4q26 region is commonly deleted in human ovarian cancer, (Sonoda et al., Genes, Chroms. and Cancer 20:320-328 (1997)) lung cancer (Shivapurkar et al., Clin. Cancer Res. 5:17-23 (1999), hepatoma (Chou et al., Cancer Letters 123:1-6 (1998); Piao et al., Int. J. Cancer 79:356-60 (1998)), cervical cancer (Mitra et al., Cancer Res. 54:4481-4487 (1994)), breast cancer (Schwendel et al., Brit. J. Cancer 78:806-811 (1998); Tirkkonen et al., Cancer Res. 57:1222-1227 (1997)), head and neck squamous cell carcinoma (Pershouse et al., Oncogene 14:369-373 (1997)), colon cancer (Arribas et al., Laboratory Invest. 79:111-122 (1999)), and oral cancer (Wang et al., Oncogene 18, 823-825 (1999)). The chromosomal location of PFM2 is thus consistent with it being a tumor suppressor gene. Given the tissue specific expression of PFM2 in ovary, PFM2 is a strong candidate for the ovarian cancer suppressor locus on 4q25-4q26.

PFM2 is also a candidate for the iris hypoplasia locus on 4q25 (Heon et al., Human Mol. Genet. 4:1435-1439 (1995)). Iris hypoplasia is an autosomal dominant disorder which is frequently associated with glaucoma.

Analysis of EST databases identified two alternative forms of PFM2 in the mouse. mPFM2a contains 2262 nt of cDNA (FIG. 3A, SEQ ID NO:5) with an open reading frame of 648 aa (FIG. 3B, SEQ ID NO:6). As shown schematically in FIG. 12A, mPFMa has 16 zinc finger domains and an intact PR domain. mPFM2b has 1127 nt of cDNA (FIG. 4A, SEQ ID NO:7) with an open reading frame of 110 aa (FIG. 4B, SEQ ID NO:8). PFM2b has no zinc finger domains and lacks the C box of the PR domain (FIG. 12A). PFM2b is likely an alternatively spliced form of PFM2 gene.

EXAMPLE III Identification and Characterization of PFM3

This example shows identification of the gene encoding the PR-domain containing polypeptide designated PFM3, and characterization of its structure, expression pattern and chromosomal location.

Sequence analysis of EST clones related to the PR domain of RIZ1 (EST clone 1853988, Accession Number AI243539) identified a PR gene designated PFM3a. The PFM3a cDNA is 2.187 kb (FIG. 5A; SEQ ID NO:9) and encodes an open reading frame of 402 aa (FIG. 5B; SEQ ID NO:10). As shown schematically in FIG. 13A, PFM3a contains a PR domain and four zinc finger domains. An alternatively spliced form of PFM3 is also expressed, designated PFM3b (FIG. 6A; SEQ ID NO:1l), that encodes an open reading frame of 318 amino acids (FIG. 6B; SEQ ID NO:12). PFM3b lacks the B and C boxes of the PR domain, as shown in FIG. 13A. These alternative structures are reminiscent of the alternative PR-plus and PR-minus products of RIZ1 and MDS1-EVI1 genes.

RT-PCR analysis was performed on human tissue RNA to examine PFM3 expression. The primers used were PFM3.1 (5′-GCTGCCTGAAAGTCTTAAAGCA-3′; SEQ ID NO:83) and PFM3.2 (5′-CAGCAAGGCACCTGGATTGGACC-3′; SEQ ID NO:84). As shown in FIG. 13B, PFM3a was detected in ovary, prostate, pancreas and kidney. Relatively weaker expression was also found in other tissues.

To map the chromosomal location of PFM3, the Standford TNG radiation hybrid panel was screened by a pair of PCR primers that amplifies PFM3 gene. This analysis mapped PFM3 to within 1000 kb from the marker SHGC-69102 on 5q21. The 5q21 region also contains the APC gene, which is deleted in colon cancer. In addition, the 5q21 region is deleted in lung cancer (Cooper et al., J. Pathology 180: 33-37 (1996); Endo et al., Brit. J. Cancer 78:612-615(1998); Wieland et al., Oncogene 12:97-102 (1996)), gastric cancer (Sanz-Ortega et al., Pathology, Research & Practice 192:1206-1210 (1996); Tamura et al., Cancer Res. 56:612-615 (1996)), MDS and AML (Pedersen, Leukemia 10: 1883-1890 (1996)), and ovarian cancer (Saretzki et al., Cancer 80:1241-1249 (1997); Tavassoli et al., Brit. J. Cancer 74, 115-119 (1996)). The chromosomal location of PFM3 is consistent with PFM3 being a tumor suppressor gene. The relatively high level expression of PFM3 in ovary suggests that PFM3 is a strong candidate for the ovarian tumor suppressor on 5q21.

EXAMPLE IV Characterization of PFM4

This example shows identification of the gene encoding the PR-domain containing polypeptide designated PFM4, and characterization of its structure and chromosomal location.

Sequence analysis of human genomic DNA databases identified a PR family member, designated PFM4, present in clone 439G8 located on 16q (GenBank Accession number AC007046). The full length cDNA sequence was assembled from predicted exons.

No EST clones of PFM4 were observed by querying publically available databases, indicating that PFM4 mRNA levels are extremely low in most tissues.

The predicted PFM4 cDNA contains four exons. The PFM4 cDNA (FIG. 7A, SEQ ID NO:13) encodes an open reading frame of 407 amino acids (FIG. 7B, SEQ ID NO:14). PFM4 protein has one PR domain at the amino-terminus, one zinc finger domain in the middle followed by a domain of approximately 100 residues, and three zinc finger domains at the C-terminus, as depicted schematically in FIG. 14.

The 100 residue domain exhibits 34% identity to the N-terminal region of the KRAB-domain containing zinc finger protein 133, ZNF133, and is thus designated PKZL, for “PR and KRAB zinc-finger protein linked.” Analysis of human genomic sequences revealed two additional zinc finger-containing genes, designated PKZL1 (FIG. 9) and PKZL2 (FIG. 10), that contain PKZL domains. The PKZL domains of these genes share 35-40% amino acid identity. ZNF133, PKZL1 and PKZL2 all map to chromosome 20. The PKZL2 genomic clone contains STS marker D20S826 which maps to 20p13.

Clone 439G8 sequence also contains the growth-arrest specific GAS11 gene which maps to 16q24 (Whitmore et al., Genomics 52:325-331 (1998)). This region is commonly deleted in prostate cancer (Cher et al., J. Urology 153:249-254 (1995); Pan et al., Prostate 36:31-38 (1998)), breast cancer (Driouch et al., Genes, Chromosomes & Cancer 19:185-191 (1997); Harada et al., Cancer 74, 2281-2286 (1994); Tsuda et al., Cancer Res. 54, 513-517 (1990)), and hepatoma (Tsuda et al., Proc. Natl. Acad. Sci. U.S.A. 87:6791-6794 (1994)).

A polymorphic allele of PFM4 was identified and used to detect loss of heterozygosity (LOH) of PFM4 gene in breast cancer. These results showed 50% loss of heterozygosity at the PFM4 locus, consistent with a role for PFM4 as a tumor suppressor gene in breast tissue.

EXAMPLE V Characterization of PFM5

This example shows identification of the gene encoding the PR-domain containing polypeptide designated PFM5, and characterization of its structure, expression pattern and chromosomal location.

An EST clone (2164030, Accession number AI570404) was identified encoding a PR-containing gene designated PFM5. A total of 2.5 kb of cDNA sequence (FIG. 8A, SEQ ID NO:15) has been obtained which encodes an open reading frame of 299 amino acids (FIG. 8B, SEQ ID NO:16). The PR domain of PFM5 is most similar to the T21B10.5 open reading frame from the C. elegans genome. In contrast to T21B10.5, which lacks zinc finger domains, PFM5 has a single zinc finger domain. Therefore, PFM5 is likely the human homolog of the C. elegens T21B10.5 gene.

Using PFM5 cDNA as a query sequence, 34 human EST sequences were identified in the database. Of these sequences, 68% (23/34) are from the human retina, suggesting retina specific expression of PFM5.

To examine PFM5 expression, mouse tissue RNAs were analyzed by RT-PCR using primers PFM5.7 (5′-AACGGACAGCTGTTCTACCGC-3′; SEQ ID NO:85) and PFM5.11 (5′-AAGTCTCTTGGGGCAGCGGAA-3′; SEQ ID NO:86). RT-PCR analysis of mouse tissues suggests that PFM5 is expressed in mouse retina and brain but not in kidney (FIG. 15B).

Human multiple tissue cDNAs tissues were amplified by PCT using primer PFM5.6 (5′-CTCCGGGAATTTCCTCTTTG-3′) (SEQ ID NO:87) and primer PFM5.7. In human tissues, PFM5 was most abundant in prostate and brain relative to other tissues, although retina was not examined (FIG. 15C).

Screening of TNG-radiation hybrid panel mapped the PFM5 gene to human chromosome 4q21.1. This region contains a susceptibility locus for Parkinson's disease (Polymeropoulos et al., Science 274, 1197-1199 (1996)), as well as tumor suppressor genes for lung cancer and mesothelioma (Shivapurkar et al., Clin. Cancer Res. 5: 17-23 (1999)), colon cancer (Arribas et al., Lab. Invest. 79:111-122 (1999), and hepatoma (Huang et al., Cancer Genet. & Cytogenet. 111:21-27 (1999)). PFM5 EST clones have also been found in colon cancer and B cell leukemia.

Therefore, based on its structure, expression pattern and chromosomal location, the PR-domain gene PFM5 is likely to be a tumor suppressor gene.

All journal article, reference and patent citations provided above, in parentheses or otherwise, whether previously stated or not, are incorporated herein by reference in their entirety.

Although the invention has been described with reference to the examples provided above, it should be understood that various modifications can be made without departing from the spirit of the invention. Accordingly, the invention is limited only by the claims. 

1. An isolated PR family member 1 (PFM1) polypeptide, comprising amino acid sequence SEQ ID NO:2.
 2. The isolated PFM1 polypeptide of claim 1, consisting of amino acid sequence SEQ ID NO:2.
 3. An isolated PR family member 1 (PFM1) polypeptide consisting of a PFM1 PR domain amino acid sequence SEQ ID NO: 18; or a PFM1 ZF domain amino acid sequence SEQ ID NO:64.
 4. The isolated PFM1 polypeptide of claim 3, consisting of amino acid sequence SEQ ID NO:18.
 5. The isolated PFM1 polypeptide of claim 3, consisting of amino acid sequence SEQ ID NO:64.
 6. An isolated PR family member 1 (PFM1) peptide, consisting of amino acid sequence SEQ ID NO:30, SEQ ID NO:32 or SEQ ID NO:34.
 7. The isolated PFM1 peptie of claim 6, consisting of amino acid sequence SEQ ID NO:30.
 8. The isolated PFM 1 peptide of claim 6, consisting of amino acid sequence SEQ ID NO:32.
 9. The isolated PFM1 peptide of claim 6, consisting of amino acid sequence SEQ ID NO:34. 